Study On The Mechanism Of Labor In The Pregnant Rat Induced By Castor Oil-Diet

Objective:Administration of castor oil-diet is a suceessful method to induction of pregnant women at term, but it's mechanism is remained unclear. On the basis of establishing an rat model, the aim of this study was to investigate the effect of castor oil-diet and/or ricinolic acid,the active component of castor oil on the synthesis of PGE₂, on the expression of COX-2 gene (clycloxygenase-2) and on the cervical ripening in pregnant rat. This study provided a new thought to discover the mystery of the initiation of labor and to prevent and treat preterm or term delivery.Methods:1. Establish an animal model of the initiation of labor induced by gavaged castor oil-diet in the prenant rat.2. Analyzed the composition of fat acid of castor oil-diet and castor oil by HPLC.3. Determined the effect of the diet on the PGE₂ levels of portal vein and peripheral blood in the pregnant rat by RIA method.4. Determined the effect of the diet and ricinoleic acid on the PGE₂ synthesis in the tissues of intestinal mucosa, amniotic membrane and placenta by RIA method.5. Determined the of the diet on the expression of COX-2 mRNA in the tissue of amniotic membrane by Northern's blot method.6. Determined the effect of the diet on the histological changes of cervical collagen and the interstitial tissues in the pregnant rat By HE & Mosson's pathologic staining.Results:1. Established the induced-labor model of the pregnant rat sucessfully.The diet could induce the initiation of labor and shorter the course of the delivery in rat.